Aircraft loaders are used for aircraft servicing and are designed to transfer containers, pallets, equipment and other types of goods to and from aircraft. Existing loaders usually have an elevator platform and a supporting assembly for supporting the platform, the supporting assembly being provided with actuating means for lifting or lowering the platform. The operation of the loader is controlled by a control station.
Loaders designed to service commercial aircraft are usually designed for use on a relatively flat, paved ground surface. The aircraft cargo floors they service are also generally level and parallel to the ground. However, surface conditions are quite different from those in the military domain. Military aircraft loaders must be able to work on an uneven, inclined, and rough ground surface. In addition, the cargo bays of the aircraft they service are rarely level with the platform loader, or parallel to the ground. When used for example in military applications or other applications where the loader has to travel on uneven or incline surfaces, aircraft loaders must be able to position their platform horizontally even when the ground is inclined. They must also be able to position their platform parallel to the aircraft, in cases where the aircraft is resting on inclined ground and goods must be loaded into the cargo bay. The aircraft loaders should also preferably allow lateral movement of the platform, so that once the loader has approached as close as possible to the aircraft access ramp, the platform can be adjusted laterally so as to fit properly with respect to the cargo opening and then facilitate loading of the goods into the aircraft. Finally, transverse and longitudinal tilting of the platform is also sought-after, for two reasons. Firstly, it allows the platform to be positioned to the cargo bay entrance opening. Secondly, it increases the manoeuvrability of the loader, which is important since the cargo bay entrance opening is often just a few inches larger than the overall dimension of the loader in its lowered position.
Already known in the art, such as in U.S. Pat. No. 4,662,809 (Sturtz et al., 1987), aircraft loaders are provided with a platform, a base frame or chassis and a scissor lift assembly therebetween for raising and lowering the platform. The base frame acts as a guiding rail for the scissor mechanism so that the lower end of the scissor legs slides within the base frame when moving from open to closed position and vice versa. The base frame also provides rigidity to the loader, and ensures that the movement of the scissor legs never deviates from the set straight lines. One drawback with such loaders is that the control over the platform's position is limited and they are thus not suited for military applications.
Other versions of aircraft loaders are provided with a pair of foldable leg assemblies supporting the loading platform, different compared to scissors assembly in that each leg assembly is used to control respectively the front and the rear of the platform. These loaders do allow for longitudinal tilting of the platform, but since they have two foldable leg assemblies, they are generally bulky, heavy, and more complex to operate. U.S. Pat. No. 4,408,739 (Buschel, 1983) and U.S. Pat. No. 5,110,153 (Kallansrude et al., 1992) give examples of such loaders.
Although several types of aircraft loaders have been developed in the past, it is believed that there is still a need for an aircraft loader better adapted to irregular or uneven ground surfaces such as the ones frequently encountered in military applications.